Evidence for chiral symmetry restoration in heavy-ion collisions

Moreau, P.; Palmese, A.; Cassing, W.; Seifert, E.; Steinert, T.; Bratkovskaya, Elena

doi:10.1016/j.nuclphysa.2017.05.030

Cited by 6 publications

(4 citation statements)

References 23 publications

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“…This regime was abruptly terminated when the system evolved through a partonic phase at energies above √ s N N ∼ 7-10 GeV, resulting in a rather sharp drop of the K + /π + ratio as a result of the chiral condensate melting and QGP formation during the collision. This microscopic transport model also predicts a smoothing of the peak with decreasing system size [45] albeit not quite matching the behaviour recently observed by NA61 in Ar+Sc collisions [42].…”

Section: Introductionsupporting

confidence: 73%

“…In another, purely hadronic transport model, the basic pattern of the energy scan of strange-to-nonstrange particle production ratios including the K + /π + and the Λ/π − horns could be reproduced because the lifetime of the (hadronic) fireball until freezeout gets shortened when increasing the energy of the collision above 30 AGeV [43]. A rather successful theoretical description of the experimental data could be given within yet another transport approach, the parton-hadron-string-dynamics (PHSD) approach [44,45] where strangeness production in the hadronic phase was enhanced by a modification of the Schwinger production rates due to partial chiral symmetry restoration. This regime was abruptly terminated when the system evolved through a partonic phase at energies above √ s N N ∼ 7-10 GeV, resulting in a rather sharp drop of the K + /π + ratio as a result of the chiral condensate melting and QGP formation during the collision.…”

Section: Introductionmentioning

confidence: 99%

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Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Blaschke

Friesen

Kalinovsky

et al. 2020

Eur. Phys. J. Spec. Top.

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Within the three-flavor PNJL and EPNJL chiral quark models we have obtained pseudoscalar meson properties in quark matter at finite temperature T and baryochemical potential μB. We compare the meson pole (Breit-Wigner) approximation with the Beth-Uhlenbeck (BU) approach that takes into account the continuum of quark-antiquark scattering states when determining the partial densities of pions and kaons. We evaluate the kaon-to-pion ratios along the (pseudo-)critical line in the T − μB plane as a proxy for the chemical freezeout line, whereby the variable x = T∕μB is introduced that corresponds to the conserved entropy per baryon as initial condition for the heavy-ion collision experiments. We present a comparison with the experimental pattern of kaon-to-pion ratios within the BU approach and using x-dependent pion and strange quark potentials. A sharp “horn” effect in the energy dependence K+∕π+ ratio is explained by the enhanced pion production at energies above √sNN=8 GeV, when the system enters the regime of meson dominance. This effect is in line with the enhancement of low-momentum pion spectra that is discussed as a precursor of the pion Bose condensation and entails the occurrence of a nonequilibrium pion chemical potential of the order of the pion mass. We elucidate that the horn effect is not related to the existence of a critical endpoint in the QCD phase diagram.

show abstract

Section: Introductionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Blaschke

Friesen

Kalinovsky

et al. 2020

Eur. Phys. J. Spec. Top.

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“…The description of the K + /π + at energies < 8 GeV has not such a clear explanation. From one hand it was shown that the partial chiral symmetry restoration could be responsible for the quick increase in the K + /π + ratio at low energies and its decrease with increasing energy (as a result of chiral condensate destruction) [2,3]. From other hand it is not clear still if the deconfinement appeared during heavy ion collision at such energies and if it coincided with the chiral phase transition.…”

Section: Introductionmentioning

confidence: 99%

Mott Dissociation and Kaon to Pion Ratio in the EPNJL Model

et al. 2021

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The behaviour of pseudoscalar mesons within the SU(3)PNJL-like models is considered for finite T and µB. We compare the pole approximation (Breit-Wigner) with the Beth-Uhlenbeck approach. We evaluate the K/π ratios along the phase transition line in the T-µB plane with constant and T /µB-dependent pion and strange quark chemical potentials. Using the model, we can show that the splitting of kaon and anti-kaon masses appears as a result of introduction of density and this explains the difference in the K + /π + ratio and K − /π − ratio at low √ sNN and their tendency to the same value at high √ sNN . A sharp "horn" effect in the K + /π + ratio is explained by the enhanced pion production which can be described by occurrence of a nonequilibrium pion chemical potential of the order of the pion mass. We elucidate that the horn effect is not related to the existence of a critical endpoint in the QCD phase diagram.

show abstract

“…A rather successful theoretical description of the experimental data could be given within yet another transport approach, the parton-hadron-string-dynamics (PHSD) approach [44,45] where strangeness production in the hadronic phase was enhanced by a modification of the Schwinger production rates due to partial chiral symmetry restoration. This regime was abruptly terminated when the system evolved through a partonic phase at energies above √ s N N ∼ 7−10 GeV, resulting in a rather sharp drop of the K + /π + ratio as a result of the chiral condensate melting and QGP formation during the collision.…”

Section: Introductionmentioning

confidence: 99%

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Blaschke,

Friesen,

Kalinovsky

et al. 2020

Preprint

View full text Add to dashboard Cite

Within the three-flavor PNJL and EPNJL chiral quark models we have obtained pseudoscalar meson properties in quark matter at finite temperature T and baryochemical potential µB. We compare the meson pole (Breit-Wigner) approximation with the Beth-Uhlenbeck (BU) approach that takes into account the continuum of quark-antiquark scattering states when determining the partial densities of pions and kaons. We evaluate the kaon-to-pion ratios along the (pseudo-)critical line in the T − µB plane as a proxy for the chemical freezeout line, whereby the variable x = T /µB is introduced that corresponds to the conserved entropy per baryon as initial condition for the heavy-ion collision experiments. We present a comparison with the experimental pattern of kaon-to-pion ratios within the BU approach and using x-dependent pion and strange quark potentials. A sharp "horn" effect in the energy dependence K + /π + ratio is explained by the enhanced pion production at energies above √ sNN = 8 GeV, when the system enters the regime of meson dominance. This effect is in line with the enhancement of low-momentum pion spectra that is discussed as a precursor of the pion Bose condensation and entails the occurrence of a nonequilibrium pion chemical potential of the order of the pion mass. We elucidate that the horn effect is not related to the existence of a critical endpoint in the QCD phase diagram.

show abstract

Evidence for chiral symmetry restoration in heavy-ion collisions

Cited by 6 publications

References 23 publications

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Mott Dissociation and Kaon to Pion Ratio in the EPNJL Model

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

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